.\"	$OpenBSD: initgroups.3,v 1.16 2015/02/05 02:33:09 schwarze Exp $
.\"
.\" Copyright (c) 1983, 1991, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.Dd $Mdocdate: February 5 2015 $
.Dt INITGROUPS 3
.Os
.Sh NAME
.Nm initgroups
.Nd initialize supplementary group IDs
.Sh SYNOPSIS
.In unistd.h
.Ft int
.Fn initgroups "const char *name" "gid_t basegid"
.Sh DESCRIPTION
The
.Fn initgroups
function uses the
.Xr getgrouplist 3
function to calculate the supplementary group IDs for the user specified in
.Fa name .
This group list is then set up for the current process using
.Xr setgroups 2 .
The
.Fa basegid
is automatically included in the group list.
Typically this value is given as the group number from the password file.
.Pp
If the groups database lists more than
.Dv NGROUPS_MAX
groups for
.Fa name
(including one for
.Fa basegid ) ,
the later groups are ignored.
.Sh RETURN VALUES
The
.Fn initgroups
function returns \-1 if it was not invoked by the superuser.
.Sh SEE ALSO
.Xr setgroups 2 ,
.Xr getgrouplist 3
.Sh HISTORY
The
.Fn initgroups
function appeared in
.Bx 4.2 .
.Sh BUGS
The
.Xr getgrouplist 3
function called by
.Fn initgroups
uses the routines based on
.Xr getgrent 3 .
If the invoking program uses any of these routines, the group structure
will be overwritten in the call to
.Fn initgroups .
